Refactor arg parsing to allow help option with parameter

qpdf/qpdf.cc

@@ -926,7 +926,6 @@ class ArgParser
     void usage(std::string const& message);
     void checkCompletion();
     void initOptionTable();
-    void handleHelpArgs();
     void handleArgFileArguments();
     void handleBashArguments();
     void readArgsFromFile(char const* filename);
@@ -3411,37 +3410,6 @@ ArgParser::readArgsFromFile(char const* filename)
     }
 }
 
-void
-ArgParser::handleHelpArgs()
-{
-    // Handle special-case informational options that are only
-    // available as the sole option.
-
-    if (argc != 2)
-    {
-        return;
-    }
-    char* arg = argv[1];
-    if (*arg != '-')
-    {
-        return;
-    }
-    ++arg;
-    if (*arg == '-')
-    {
-        ++arg;
-    }
-    if (! *arg)
-    {
-        return;
-    }
-    if (this->help_option_table.count(arg))
-    {
-        (this->*(this->help_option_table[arg].bare_arg_handler))();
-        exit(0);
-    }
-}
-
 void
 ArgParser::parseRotationParameter(std::string const& parameter)
 {
@@ -3601,22 +3569,23 @@ void
 ArgParser::parseOptions()
 {
     checkCompletion();
-    if (! this->bash_completion)
-    {
-        handleHelpArgs();
-    }
     handleArgFileArguments();
     for (cur_arg = 1; cur_arg < argc; ++cur_arg)
     {
+        bool help_option = false;
+        auto oep = this->option_table->end();
         char* arg = argv[cur_arg];
+        char* parameter = nullptr;
+        std::string o_arg(arg);
+        std::string arg_s(arg);
         if (strcmp(arg, "--") == 0)
         {
             // Special case for -- option, which is used to break out
             // of subparsers.
-            OptionEntry& oe = (*this->option_table)["--"];
+            oep = this->option_table->find("--");
-            if (oe.bare_arg_handler)
+            if (oep == this->option_table->end())
             {
-                (this->*(oe.bare_arg_handler))();
+                throw std::logic_error("ArgParser: -- handler not registered");
             }
         }
         else if ((arg[0] == '-') && (strcmp(arg, "-") != 0))
@@ -3627,7 +3596,6 @@ ArgParser::parseOptions()
                 // Be lax about -arg vs --arg
                 ++arg;
             }
-            char* parameter = 0;
             if (strlen(arg) > 0)
             {
                 // Prevent --=something from being treated as an empty
@@ -3640,15 +3608,36 @@ ArgParser::parseOptions()
                 *parameter++ = 0;
             }
 
-            std::string arg_s(arg);
+            arg_s = arg;
-            if (arg_s.empty() ||
+            if (! (arg_s.empty() || (arg_s.at(0) == '-')))
-                (arg_s.at(0) == '-') ||
-                (0 == this->option_table->count(arg_s)))
             {
-                usage(std::string("unknown option --") + arg);
+                oep = this->option_table->find(arg_s);
             }
 
-            OptionEntry& oe = (*this->option_table)[arg_s];
+            if ((! this->bash_completion) &&
+                (argc == 2) && (cur_arg == 1) &&
+                (oep == this->option_table->end()))
+            {
+                // Handle help option, which is only valid as the sole
+                // option.
+                oep = this->help_option_table.find(arg_s);
+                help_option = true;
+            }
+        }
+        else
+        {
+            // The empty string maps to the positional argument
+            // handler.
+            oep = this->option_table->find("");
+            parameter = arg;
+        }
+
+        if (oep == this->option_table->end())
+        {
+            usage("unrecognized argument " + o_arg);
+        }
+
+        OptionEntry& oe = oep->second;
         if ((oe.parameter_needed && (0 == parameter)) ||
             ((! oe.choices.empty() &&
               ((0 == parameter) ||
@@ -3692,20 +3681,9 @@ ArgParser::parseOptions()
         {
             (this->*(oe.param_arg_handler))(parameter);
         }
-        }
+        if (help_option)
-        else if (0 != this->option_table->count(""))
         {
-            // The empty string maps to the positional argument
+            exit(0);
-            // handler.
-            OptionEntry& oe = (*this->option_table)[""];
-            if (oe.param_arg_handler)
-            {
-                (this->*(oe.param_arg_handler))(arg);
-            }
-        }
-        else
-        {
-            usage(std::string("unknown argument ") + arg);
         }
     }
     if (this->bash_completion)